Miami — A Florida judge’s decision to invalidate a portion of the state’s map of congressional districts is placing the Republican-controlled Legislature under a judicial microscope.

At issue is whether lawmakers in Tallahassee intentionally circumvented a requirement of Florida’s constitution that they avoid engaging in any partisan gerrymandering while drawing new election boundaries.

In a decision announced late Thursday, Circuit Judge Terry Lewis ruled that two of the state’s 27 congressional districts had been drawn with the intention of benefiting the Republican Party, and ordered that the districts be redrawn.

State lawmakers are expected to appeal, and the case could ultimately go to the Florida Supreme Court. The districts are those of US Rep. Corinne Brown, a Jacksonville Democrat, and US Rep. Daniel Webster, an Orlando Republican.

It is unclear whether the court-ordered redrawing will shift the balance of power within Florida’s congressional delegation. Republicans currently hold 17 seats and Democrats 10.

In a 41-page decision, Judge Lewis said a group of Republican operatives and consultants conspired to circumvent the requirements of a 2010 state constitutional amendment that banned the use of political gerrymandering in the drawing of election districts.

“What is clear to me from the evidence … is that this group of Republican political consultants or operatives did in fact conspire to manipulate and influence the redistricting process,” Lewis wrote.

“They made a mockery of the Legislature’s proclaimed transparent and open process of redistricting by doing all of this in the shadow of that process,” he said.

Although the judge admitted that he had seen no direct evidence of partisan intent by individual lawmakers, he said he found circumstantial evidence that operatives acting behind the scenes were able to infiltrate and influence the Legislature.

“They managed to taint the redistricting process and the resulting map with improper partisan intent,” the judge wrote. “There is just too much circumstantial evidence of it, too many coincidences, for me to conclude otherwise.”

There is nothing illegal about engaging in political gerrymandering. It does not violate the US Constitution. Indeed, most state lawmakers in other states – both Democrats and Republicans – use their political power to try to redraw state and federal election districts in ways that benefit their own party and their own incumbent officials.

But Florida is different. In 2010, state voters amended the Florida constitution to dramatically restrict the lawmakers’ discretion in drawing new election boundaries.

The amendment barred the drawing of any map with the intent to favor or disfavor a political party or incumbent official.

Following the amendment, state lawmakers went about the task of redrawing districts for the 2012 elections.

The League of Women Voters, Common Cause, and other groups attempted to follow the new process and then filed a lawsuit charging that the Republican Party had circumvented the open and fair process mandated by the Florida constitution.

On Thursday, Judge Lewis announced that he agreed with that assessment.

In invalidating Congresswoman Brown’s district boundaries, Lewis said the district was bizarrely shaped as it wound its way through African-American neighborhoods stretching from Jacksonville to Orlando. At one point the district is no wider than Highway 17, the judge said.

In contrast, the Florida constitution requires that districts be as compact as possible.

Under the invalidated plan, Brown’s district became a majority-minority district, potentially benefiting the reelection chances of Brown, a Democrat. But Judge Lewis said shifting African-American voters into Brown’s district was done with the intent of benefiting the Republican Party.

During a 12-day trial, Florida officials said they made the move to avoid a potential Voting Rights Act lawsuit on behalf of African-American voters in Brown’s district.

“That justification is not compelling, without some showing that it was legally necessary to create a majority-minority district,” Lewis said.

Instead, the judge concluded that it was done to increase the possibility of a Republican victory in an adjacent district. The judge noted that by shifting African-American voters into Brown’s district, registered Democrats in the neighboring district dropped from 36 percent to 35 percent.

In a statement, Congresswoman Brown called Lewis’s decision “seriously flawed.”

She said the current map of her district is essentially the same as the map drawn under court-order and upheld by the US Supreme Court under principles of the federal Voting Rights Act.

In invalidating Congressman Webster’s 10th District map, Lewis objected to a decision by the Legislature to graft an “appendage” from neighboring districts onto Webster’s district.

The “appendage” is an area with a white majority. Lawmakers sought to justify including this area in Webster’s district by arguing that its inclusion in either of two neighboring districts would have reduced the political clout of minority voters in either of those districts.

“I cannot agree,” Lewis said. “While the creation of a Hispanic influence district … may be a legitimate goal, there is no evidence before me to suggest that it was entitled to [minority] protection.”

The influx of voters from the “appendage” lowered the number of registered Democrats in Webster’s district from 37.3 percent to 36.8 percent, the judge said. This amounted to an impermissible partisan consideration, the judge said.

The judge rejected arguments that seven other congressional districts near Tampa and South Florida must be redrawn.

The judge noted that any effort to redraw the two invalidated districts would also involve redrafting voting boundaries for surrounding districts as well.